build-style/cmake: pass DESTDIR as env var to make install
build-style/cmake: pass DESTDIR as env var to make install

this ensures that the build-style also works with ninja when setting
-GNinja and make_cmd=ninja

necrophcodr/void-packages,necrophcodr/void-packages,necrophcodr/void-packages,necrophcodr/void-packages,necrophcodr/void-packages